What are Those Weird Spirals in Mars' Surface?

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Giant coils of lava on Mars suggest a mysterious network of
valleys on the planet was born from volcanoes, researchers say.

The origin of the Athabasca Valles region near the equator of
Mars has been debated for more than a decade. Some
researchers have proposed that lava
once shaped the valleys, while others have thought ice was
responsible.

The way the ground there is patterned with multisided polygons
suggests that either fire or ice could be the culprit -- such
patterns of cracks might have formed due to seasonal fluctuations
in temperature if the surface there was rich in ice, but also
might have arose as lava cooled and fractured.

Now high-resolution images beamed back by NASA's Mars
Reconnaissance Orbiter of the Red Planet have revealed 269
spirals of lava that researchers say cannot be explained by
ice-related activity.

"This is the first time lava coils have been identified on an
extraterrestrial setting," study lead author Andrew Ryan at
Arizona State University told SPACE.com. "The most surprising
thing about these features when I first saw them was how
well-preserved they are."

Ryan spotted all these coils, ranging from 16 to 98 feet wide (5
to 30 meters), by eye.

"You can't see them unless you zoom in really close, and even
then they're really subtle -- it's pretty dusty there, so the
images are just a pale gray color, and they don't really jump out
until you boost the contrast, so it's not surprising at all to me
that they've been overlooked before," Ryan said.

These spirals resemble lava coils on Earth, such as those forming
on the surface of Hawaiian lava flows. "These can only be
explained by lava processes," Ryan said. "There are no known
processes to twist ice around on that scale."

Future modeling of how these spirals formed can help figure out
the composition of these lavas, "which can tell you about the
composition of the Martian crust and mantle, things we don't know
much about," Ryan said.

Mars is the home of the largest
known volcano in the solar system, Olympus Mons, which towers
over Mars' western hemisphere. At 16 miles (25 km) high, it
is about three times as tall as Mount Everest, Earth's highest
mountain.

The $720 million Mars Reconnaissance Orbiter launched in
September 2005.

The scientists detailed their findings in the April 27 issue of
the journal Science.